Published 4:00 am, Thursday, January 9, 2003

One child has been hospitalized and seven others were made ill in an outbreak of potentially deadly E. coli bacteria at a popular San Francisco day care center.

The illnesses occurred before the Christmas break at the private Katherine Michiels School in the Mission District and were confined to infants and toddlers enrolled in a program serving children between the ages of 3 months and 2 years, and to a sibling of one of those children.

Although the outbreak appears to have ended, and the affected children are recovering, the city Health Department has barred the return of any of the infected children until they pass tests showing they have completely cleared the bacteria from their systems. That can take an average of three weeks.

"It looks like a person-to-person spread that took place over several weeks in December," said Dr. Tomas Aragon, director of community health epidemiology and disease control at the San Francisco Department of Public Health. "It happened, and died out, before Christmas vacation."

No other cases of the illness at the day care center or anywhere else in the city have been reported, he said.

Aragon confirmed that the children were apparently exposed to a strain of the bacteria E. coli O157/H7 that is particularly dangerous to youngsters. However, only one child was made seriously ill by the bug.

The outbreak was reported on Christmas Eve after a girl who was hospitalized tested positive for the bacteria, as did a second child who had a milder illness. The unidentified girl is still hospitalized after a life- threatening bout of hemolytic uremic syndrome, a form of kidney failure that is the most serious complication of an E. coli infection.

Aragon said a city environmental health officer had been sent to inspect the school, which has operated in the city for 27 years. "We couldn't see anything that would cause concern," he said. "They run a pretty tight ship."

Although E. coli has been traced to contaminated ground beef, juices and salads, investigators believe the bug in this case was picked up by a family that had traveled to a farm, where the bacteria are shed by healthy cattle. The germs were subsequently spread among the toddlers.

"It's hard to keep hygiene perfect in that group," Aragon said. "They are not all potty trained."

During the Christmas break, Katherine Michiels staffers contacted parents of the 102 children who attend the day care center, starting with the 22 enrolled in the infants and toddlers program. City disease detectives found that 13 of those children had diarrhea symptoms within the past month.

According to a letter sent to parents by the city, seven of 10 infants and toddlers who had diarrhea tested positive for E. coli O157/H7, although only two children became sick enough for their parents to seek medical attention. One of the sick children's siblings, who did not attend the day care center, also tested positive for E. coli.

Among another group of 62 older children, enrolled in a daytime preschool program, 10 reported having diarrhea symptoms in the past month, but none tested positive for the dangerous pathogen.

School founder Katherine Michiels said it had been an anxious period for the closely knit group of parents who send their children to her day care center. "We feel very fortunate we had only one case with a severe reaction," she said.

E. coli O157/H7 is a renegade strain of a common intestinal bacteria that epidemiologists had never seen until outbreaks in Michigan and Oregon in 1982. It burst into public awareness in 1993 after four children died after eating hamburgers at a Jack-in-the-Box restaurant in the Seattle area.

Since then, it has been responsible for several widely publicized outbreaks,

including one traced to unpasteurized Odwalla fruit juices in November 1996 that killed one Colorado child and sickened 65 other people across the western United States.

According to the federal Centers for Disease Control, the bug is now responsible for an average of 61 deaths and 73,000 cases of food-borne illness each year.